Control system for cigarette making machine



April 28, 1964 c. c. MARTIN 3,130,733

CONTROL SYSTEM FOR CIGARETTE MAKING MACHINE Filed June 7, 1960 INVENTOR entrance of the cigarette rod forming apparatus.

United States Patent 3,130,733 CONTROL SYSTEM FOR CIGARETTE -MAKING MACHINE Carlos C. Martin, Hiiliard, Ohio, assignor to Industrial Nucleonics Corporation, a corporation of Ohio Filed June '7, 1960, Ser. No. 34,494 3 Claims. (Cl. 1s1 21 This invention relates to cigarette manufacture, and more particularly it relates to improvements in a system for automatically controlling the weight per unit length of the cigarette rod formed by a continuous cigarette making machine.

In a relatively new type of cigarette making machine, a stream of tobacco is delivered to a point near the The Weight per unit length of said stream is arranged to be somewhat in excess of the desired weight per unit length of the tobacco filler within the Wrapped cigarette rod. Specifically, the excess is desirably large enough to encompass all the unavoidable variations which occur as the stream is being formed from cut tobacco. Thereupon, at the point aforesaid, the excess tobacco in the stream is removed. In a preferred type of removal device, removal of the excess is effected by a rotating knife which slices off the top layer of the stream, and in theory thereby removes most of the lumps, bunches and other irregularities in the stream Which would otherwise be propagated into the finished cigarette rod. Means are provided for adjusting the depth at which the knife dips into the channel which carries the stream, and it has been proposed that the knife position be automatically controlled in response to measurements of the cigarette rod.

The knife position control device aforesaid, on a machine of the type described, has an inherent theoretical advantage over the conventional feeder control systems now in use. This advantage obtains by reason of the short transportation delay, that is, the time required for the stream leveled by the knife, to be formed into the cigarette rod and measured by the gauge. However, the theoretically possible improvements in cigarette quality have not been achieved in practice.

In retrospect, it is now known that much of the difficulty previously encountered was the result of non-uniformity of the feed. Previously, the operation of the tobacco feed mechanism, which determines the rate at which the tobacco was fed to the stream, was regulated to some extent by utilizing limit switches actuated on overtravel of the knife position adjusting mechanism. Thus when the knife adjustment reached a point near the limit of travel, an incremental increase or decrease in the speed of the tobacco feed mechanism would result.

In accordance with this invention it has been found that the effectiveness of the knife control is much more de pendent on slight variations in the tobacco feed than had heretofore been realized. That is to say, it appears that there is an optimum value of the weight per unit length of the tobacco stream which is presented to the equalizer knife for levelling thereby. Moreover, this optimum value is subject to variation depending on the individual machine and the physical characteristics of the tobacco to be processed.

Hence I provide what may be termed a cascade conof the feed regulating controller.

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trol system employing means responsive to the weight per unit length of the cigarette rod for controlling the position of the knife, and means responsive in turn to the position of the knife for controlling the tobacco feed. The knife control is designed to operate with a high velocity constant, taking full advantage of the short transportation delay to level out the short term variations in the stream, whereas the feed control maintains the unleveled stream at an optimum weight value such that the knife control is enabled to operate in its most effective range. An important feature of the invention is the provision of means for adjusting the precise operating point This permits the control system to be adapted to the individual variations of different cigarette making machines, and different grades and mixtures of tobacco processed thereby. Thus, indi rectly, the operating range of the knife adjustment is always maintained in the region where the control thereof is most efficient and effective.

Therefore, it is the object of this invention to provide a new and improved control system for cigarette making machines whereby short term variations as well as mean value variations in the weight per unit length of the cigarette rod are substantially reduced.

It is also an object to provide, in combination with a machine for forming a stream of tobacco and a device for removing a variable portion of said stream, a control system including means for automatically adjusting said removal means to maintain the remainder of said stream at a substantially constant weight, and means for automatically adjusting said stream forming means whereby the stream is continuously adapted to be operated on by said removal means in the most effective manner.

It is another object to provide a control system in accordance with the aforesaid objects which is readily adjustable for optimum performance on machines and materials having different characteristics.

Further objects and advantages will become apparent in the following detailed description of one preferred embodiment of the invention taken in connection with the appended drawings, in which:

FIG. 1 is a simplified perspective showing of a cigarette making apparatus having a control system in accordance with the invention.

FIG. 2 is a circuit diagram illustrating one preferred form of knife position transducer arrangement suitable for use in the control system of FIG. 1.

Referring now to the drawings, FIG. 1 is a simplified schematic showing of a specific type of cigarette making machine, for example, a machine such as the Garant" Twin Rod Spiral Machine which is manufactured by Hauni Werke Korber & Company, KG., Hamburg, Germany. Herein the numeral 10 indicates a conventional feed mechanism which showers cut tobacco onto a horizontal belt 12 passing under a first drum 14 having a peripheral groove (not shown).

The tobacco on belt 12 is pressed into the groove in drum 14 and retained therein by partial vacuum, supplied through the hollow interior of the drum. The vacuum is gradually removed as the tobacco stream is carried over the drum and under a rotating equalizer knife 16. The leveled tobacco stream 18 is then transferred to the usual traveling paper web 20 and carried thereon by the 3 usual tube belt 22 into the rod former 24 which forms the cigarette rod 26, in an arrangement similar to that shown in FIG. 4 of Patent No. 2,868,211.

The excess tobacco 28, including most of the bunches and irregularities in the tobacco stream carried over drum 14, is received by a second, carded drum 3%) rotating in the same direction as drum 14 but at only one-fourth the speed thereof, or as is seen in the drawing, when the second drum 30 rotates through an angle 0, the first drum 14 rotates through an angle of 40. A picker roller 32 coacting with drum 36 removes the tobacco 28 there from, and the same is forthwith returned to belt 12 to merge with the tobacco supplied from the feeder 10.

The equalizer knife 16 is adjustable through a distance of about one millimeter toward and away from the drum 14 through a lever system 34 including a cam 36 and follower 38 device. In accordance with this invention the position of the cam 36 is continuously readjusted by a measuring and feedback control system comprising a suitable gauge transducer 40 responsive to the weight per unit length of the rod 26, an amplifier-controller device 42-44, and a servo motor 46 and gear box 48 for driving the cam 36. The gauge-controller system 40 t8 is preferably of the type described in the copending application ,of Philip Spergel and Sidney A. Radley, Serial No. 641,414, filed February 20, 1957, now Patent No. 2,955,206. The gauge transducer 46 preferably comprises a radiation source 40a and a radiation detector 40b in an arrangement somewhat as described in the copending application of Sidney A. Radley and Philip Spergel, Serial No. 641,357, originally filed February 20, 1957, originally issued as Patent No. 2,954,755 and now reissued as Reissue Patent No. Re. 25,476. As is set forth in said Patent No. 2,955,206, the control system employs a tachometer 46a coupled to or integral with the servo motor and forming part of an internal feedback loop whereby the control system functions as a special analog device for computing the time integral of the error in weight per unit length of the cigarette rod 26 and repositioning the cam 36 in accordance with the value of said integral. Further in accordance with the invention there is provided means for generating an analog signal representing the position of the cam 36. In one preferred form of the invention as illustrated, a slidewire potentiometer 50 is mechanically connected to the cam as indicated by the dotted line 52. The potentiometer is electrically connected by conductors 54 to a controller 56. The controller 56 includes circuits for suitably actuating a motor 58 which is connected through a gear box 60 and chain and sprocket arrangement 62 to the control shaft 64 of the feeder mechanism 10. The feeder 16 is driven by a variable speed mechanism in a manner similar to that which is described and illustrated in the above-referenced reissue Patent No. Re. 25,476, the angular position of shaft 64 thereby determining the rate at which the feeder deposits tobacco on belt 12. The controller 56 may be of the same type as the controller 44, in which case the motor 58 is equipped with a tachometer 58a. Alternately, the controller 56 may be of the type which is illustrated in FIG. 2 of Patent No. 2,895,888, in which case the tachometer 58a is omitted.

An essential feature of the present invention is the system by which the knife position indicator signal is derived and presented to the controller 56. This system is best understood by considering the preferred and specific device shown in FIG. 27 Herein it is seen that the slidewire potentiometer 50 is connected as one arm of a bridge circuit energized by a voltage source represented by the battery 66 through a voltage dropping rheostat 68. The other arm of the bridge comprises a further potentiometer 70. The variable tap 50a of the potentiometer 56 is mechanically coupled by connection 52 to the equalizer knife adjusting cam 36, whereas the variable tap 70a of potentiometer 70 is mechanically adjustable by means of a control knob 72 which is movable with respect to a graduated position indicator 72a. By this system, a voltage analog of the knife position is obtained from the tap 56a of potentiometer 50, and similarly a voltage analog of any selected knife position is obtained from tap 76a. The difference in these two voltages constitutes an error signal e which energizes the tobacco feeder controller 56.

In operation, first assume that an optimum stream of tobacco is flowing on belt 12, that the knife 16 is in, say, the center of its positional range, that the control knob 72 has been set, say, in the center position and that the cigarette rod 26 has the correct weight per unit length. Under these conditions the voltage at potentiometer tap 563a is equal to the voltage at potentiometer tap 7 flu, and accordingly the difference or error signal e input to controller 56 (FIG. 1) is zero. Accordingly, no action is taken by the control system. Now if for some reason the rod 26 becomes light, say, the controller 44 will raise the knife 16, allowing more tobacco to pass into the rod former 24 but returning less tobacco around drum 30 to belt 12. It is apparent that the return flow of tobacco constitutes a small reservoir which can be manipulated by the equalizer knife control so as to iron out medium or short-term variations in the feed.

If it is the case that the light condition of the rod aforesaid results from an insufficiency in the mean flow of tobacco on belt 12, the knife control action becomes regenerative. That is, the raising of the knife results in less return flow 28, which in turn decreases the amount of tobacco carried by drum 14, requiring a further raising of knife 16 by the controller, and so on. Since the raising of the knife results in a displacement of slidewire tap 50a, the potential thereof will no longer be equal to the potential at potentiometer tap 70a, and the difference voltage e will no longer be zero. Hence the controller 56 will take action to correct the speed of the feeder 10. When the stream of tobacco on belt 12 has been restored to the proper weight per unit length, the knife controller will return the knife 16 to its original position in the center of its optimum operating range.

It is apparent that when the opposite situation occurs and the cigarette rod 26 becomes light, an opposite sequence of action will be taken by the two control devices.

Depending on the physical characteristics of the tobacco and the individual characteristics of a particular machine, the optimum operating point for the knife may not be in the center of its range of adjustment. This is ordinarily determined by automatic variance computations, in the manner described in the copending application of Sidney A. Radley and Philip Spergel, Serial No. 668,935, new Patent No. 2,965,300, with the set point knob '72 in various positions. In this way proper settings for each machine and each type of tobacco to be processed thereby are made available to the machine operator.

The embodiment of the invention herein illustrated and described can obviously be modified in many forms without departing from the essential characteristics set forth in the appended claims.

What is claimed is:

1. In cigarette making apparatus including adjustable means for forming a gross tobacco stream, adjustable means for removing the excess in said stream to form a filler from the remainder of said stream after said excess is removed therefrom, and means for forming said filler into a wrapped cigarette rod, the improvement comprising means responsive to the weight per unit length of said rod for controlling the position of said adjustable removal means, and means continuously responsive to said position for controlling said stream forming means. i

2. Apparatus as in claim 1 wherein said position responsive means comprises means for generating a first analog signal indicative of the position of said adjustable removal means, means for generating a second analog signal indicative of a selected position of said adjustable removal means, and means energized by the difference between said first and second analog signals for adjusting 5 the Weight per unit length of said gross tobacco stream.

3. Apparatus as in claim 2 wherein said second analog signal generating means includes means for adjusting the value of said second analog signal, and means for visually indicating the selected position of said removal means 10 represented thereby.

References Cited in the file of this patent UNITED STATES PATENTS Hawkins June 28, 1932 Stephano June 20, 1939 Rault Nov. 24, 1953 Lanore May 31, 1960 Spergel et al Oct. 14, 1960 Molins et a1 May 14, 1963 FOREIGN PATENTS Australia Oct. 17, 1952 

1. IN CIGARETTE MAKING APPARATUS INCLUDING ADJUSTABLE MEANS FOR FORMING A GROSS TOBACCO STREAM, ADJUSTABLE MEANS FOR REMOVING THE EXCESS IN SAID STREAM TO FORM A FILLER FROM THE REMAINDER OF SAID STREAM AFTER SAID EXCESS IS REMOVED THEREFROM, AND MEANS FOR FORMING SAID FILLER INTO A WRAPPED CIGARETTE ROD, THE IMPROVEMENT COMPRISING MEANS RESPONSIVE TO THE WEIGHT PER UNIT LENGTH OF SAID ROD FOR CONTROLLING THE POSITION OF SAID ADJUSTABLE REMOVAL MEANS, AND MEANS CONTINUOUSLY RESPONSIVE TO SAID POSITION FOR CONTROLLING SAID STREAM FORMING MEANS. 